Technical Field
The invention relates to a printing head assembly, and particularly relates to a printing head assembly having at least two nozzle heads.
Related Art
In recent years, along with development of technology, many methods for constructing a physical three-dimensional (3D) model by using an additive manufacturing technology such as a layer-by-layer model construction are developed. Generally, the additive manufacturing technology is to convert design data of the 3D model constructed by using software such as computer aided design (CAD) into a plurality of successively stacked thin (quasi-2D) cross-sectional layers. Meanwhile, many technical means used for forming the thin cross-sectional layers are provided. For example, a printing head assembly of a 3D printing device can move above a platform along an XY-plane according to spatial coordinates XYZ constructed by the design data of the 3D model, such that a printing material forms a correct shape of the cross-sectional layer, and then the printing head is driven to move along a Z-axis layer-by-layer, such that the cross-sectional layers are gradually stacked, and a 3D object is formed after the printing material is cured layer-by-layer.
There is a plurality of methods for forming the printing material on the platform, and one method is to fabricate the printing material into a filament, and a driving unit is used to push the filament into a heating type nozzle head. The filament is heated into a molten state in the nozzle head, and is then squeezed out from the nozzle head, such that the printing material is stacked on the platform layer-by-layer to form the 3D object. Moreover, some printing devices may also adopt a printing head assembly having two nozzle heads, and in collaboration with filaments of different colors, thus the 3D object produced by the printing device may have a plurality of colors. In the commonly used printing head assembly, height levels of the two nozzle heads are generally the same. However, when the printing head assembly conducts printing through one of the nozzle heads in collaboration with the corresponding filament, another non-used nozzle head located at the same height level or the filament presenting a molten state therein is liable to contact the 3D object to cause a flaw of the 3D object. Therefore, a printing effect of the printing head assembly is poor.